module Prism
  # This represents a node in the tree. It is the parent class of all of the
  # various node types.
  class Node
    # A pointer to the source that this node was created from.
    attr_reader :source
    private :source

    # A unique identifier for this node. This is used in a very specific
    # use case where you want to keep around a reference to a node without
    # having to keep around the syntax tree in memory. This unique identifier
    # will be consistent across multiple parses of the same source code.
    attr_reader :node_id

    # A Location instance that represents the location of this node in the
    # source.
    def location
      location = @location
      return location if location.is_a?(Location)
      @location = Location.new(source, location >> 32, location & 0xFFFFFFFF)
    end

    # The start offset of the node in the source. This method is effectively a
    # delegate method to the location object.
    def start_offset
      location = @location
      location.is_a?(Location) ? location.start_offset : location >> 32
    end

    # The end offset of the node in the source. This method is effectively a
    # delegate method to the location object.
    def end_offset
      location = @location
      location.is_a?(Location) ? location.end_offset : ((location >> 32) + (location & 0xFFFFFFFF))
    end

    # Returns all of the lines of the source code associated with this node.
    def source_lines
      location.source_lines
    end

    # An alias for source_lines, used to mimic the API from
    # RubyVM::AbstractSyntaxTree to make it easier to migrate.
    alias script_lines source_lines

    # Slice the location of the node from the source.
    def slice
      location.slice
    end

    # Slice the location of the node from the source, starting at the beginning
    # of the line that the location starts on, ending at the end of the line
    # that the location ends on.
    def slice_lines
      location.slice_lines
    end

    # An bitset of flags for this node. There are certain flags that are common
    # for all nodes, and then some nodes have specific flags.
    attr_reader :flags
    protected :flags

    # Returns true if the node has the newline flag set.
    def newline?
      flags.anybits?(NodeFlags::NEWLINE)
    end

    # Returns true if the node has the static literal flag set.
    def static_literal?
      flags.anybits?(NodeFlags::STATIC_LITERAL)
    end

    # Similar to inspect, but respects the current level of indentation given by
    # the pretty print object.
    def pretty_print(q)
      q.seplist(inspect.chomp.each_line, -> { q.breakable }) do |line|
        q.text(line.chomp)
      end
      q.current_group.break
    end

    # Convert this node into a graphviz dot graph string.
    def to_dot
      # @type self: node
      DotVisitor.new.tap { |visitor| accept(visitor) }.to_dot
    end

    # Returns a list of nodes that are descendants of this node that contain the
    # given line and column. This is useful for locating a node that is selected
    # based on the line and column of the source code.
    #
    # Important to note is that the column given to this method should be in
    # bytes, as opposed to characters or code units.
    def tunnel(line, column)
      queue = [self] #: Array[Prism::node]
      result = []

      while (node = queue.shift)
        result << node

        node.compact_child_nodes.each do |child_node|
          child_location = child_node.location

          start_line = child_location.start_line
          end_line = child_location.end_line

          if start_line == end_line
            if line == start_line && column >= child_location.start_column && column < child_location.end_column
              queue << child_node
              break
            end
          elsif (line == start_line && column >= child_location.start_column) || (line == end_line && column < child_location.end_column)
            queue << child_node
            break
          elsif line > start_line && line < end_line
            queue << child_node
            break
          end
        end
      end

      result
    end

    # Returns the first node that matches the given block when visited in a
    # depth-first search. This is useful for finding a node that matches a
    # particular condition.
    #
    #     node.breadth_first_search { |node| node.node_id == node_id }
    #
    def breadth_first_search(&block)
      queue = [self] #: Array[Prism::node]

      while (node = queue.shift)
        return node if yield node
        queue.concat(node.compact_child_nodes)
      end

      nil
    end

    # Returns a list of the fields that exist for this node class. Fields
    # describe the structure of the node. This kind of reflection is useful for
    # things like recursively visiting each node _and_ field in the tree.
    def self.fields
      # This method should only be called on subclasses of Node, not Node
      # itself.
      raise NoMethodError, "undefined method `fields' for #{inspect}" if self == Node

      Reflection.fields_for(self)
    end

    # --------------------------------------------------------------------------
    # :section: Node interface
    # These methods are effectively abstract methods that must be implemented by
    # the various subclasses of Node. They are here to make it easier to work
    # with typecheckers.
    # --------------------------------------------------------------------------

    # Accepts a visitor and calls back into the specialized visit function.
    def accept(visitor)
      raise NoMethodError, "undefined method `accept' for #{inspect}"
    end

    # Returns an array of child nodes, including `nil`s in the place of optional
    # nodes that were not present.
    def child_nodes
      raise NoMethodError, "undefined method `child_nodes' for #{inspect}"
    end

    alias deconstruct child_nodes

    # Returns an array of child nodes, excluding any `nil`s in the place of
    # optional nodes that were not present.
    def compact_child_nodes
      raise NoMethodError, "undefined method `compact_child_nodes' for #{inspect}"
    end

    # Returns an array of child nodes and locations that could potentially have
    # comments attached to them.
    def comment_targets
      raise NoMethodError, "undefined method `comment_targets' for #{inspect}"
    end

    # Returns a string representation of the node.
    def inspect
      raise NoMethodError, "undefined method `inspect' for #{inspect}"
    end

    # Sometimes you want to check an instance of a node against a list of
    # classes to see what kind of behavior to perform. Usually this is done by
    # calling `[cls1, cls2].include?(node.class)` or putting the node into a
    # case statement and doing `case node; when cls1; when cls2; end`. Both of
    # these approaches are relatively slow because of the constant lookups,
    # method calls, and/or array allocations.
    #
    # Instead, you can call #type, which will return to you a symbol that you
    # can use for comparison. This is faster than the other approaches because
    # it uses a single integer comparison, but also because if you're on CRuby
    # you can take advantage of the fact that case statements with all symbol
    # keys will use a jump table.
    def type
      raise NoMethodError, "undefined method `type' for #{inspect}"
    end

    # Similar to #type, this method returns a symbol that you can use for
    # splitting on the type of the node without having to do a long === chain.
    # Note that like #type, it will still be slower than using == for a single
    # class, but should be faster in a case statement or an array comparison.
    def self.type
      raise NoMethodError, "undefined method `type' for #{inspect}"
    end
  end
  <%- nodes.each do |node| -%>

  <%- node.each_comment_line do |line| -%>
  #<%= line %>
  <%- end -%>
  class <%= node.name -%> < Node
    # Initialize a new <%= node.name %> node.
    def initialize(<%= ["source", "node_id", "location", "flags", *node.fields.map(&:name)].join(", ") %>)
      @source = source
      @node_id = node_id
      @location = location
      @flags = flags
      <%- node.fields.each do |field| -%>
      <%- if Prism::Template::CHECK_FIELD_KIND && field.respond_to?(:check_field_kind) -%>
      raise <%= field.name %>.inspect unless <%= field.check_field_kind %>
      <%- end -%>
      @<%= field.name %> = <%= field.name %>
      <%- end -%>
    end

    # def accept: (Visitor visitor) -> void
    def accept(visitor)
      visitor.visit_<%= node.human %>(self)
    end

    # def child_nodes: () -> Array[nil | Node]
    def child_nodes
      [<%= node.fields.map { |field|
        case field
        when Prism::Template::NodeField, Prism::Template::OptionalNodeField then field.name
        when Prism::Template::NodeListField then "*#{field.name}"
        end
      }.compact.join(", ") %>]
    end

    # def compact_child_nodes: () -> Array[Node]
    def compact_child_nodes
      <%- if node.fields.any? { |field| field.is_a?(Prism::Template::OptionalNodeField) } -%>
      compact = [] #: Array[Prism::node]
      <%- node.fields.each do |field| -%>
      <%- case field -%>
      <%- when Prism::Template::NodeField -%>
      compact << <%= field.name %>
      <%- when Prism::Template::OptionalNodeField -%>
      compact << <%= field.name %> if <%= field.name %>
      <%- when Prism::Template::NodeListField -%>
      compact.concat(<%= field.name %>)
      <%- end -%>
      <%- end -%>
      compact
      <%- else -%>
      [<%= node.fields.map { |field|
        case field
        when Prism::Template::NodeField then field.name
        when Prism::Template::NodeListField then "*#{field.name}"
        end
      }.compact.join(", ") %>]
      <%- end -%>
    end

    # def comment_targets: () -> Array[Node | Location]
    def comment_targets
      [<%= node.fields.map { |field|
        case field
        when Prism::Template::NodeField, Prism::Template::LocationField then field.name
        when Prism::Template::OptionalNodeField, Prism::Template::NodeListField, Prism::Template::OptionalLocationField then "*#{field.name}"
        end
      }.compact.join(", ") %>] #: Array[Prism::node | Location]
    end

    # def copy: (<%= (["?node_id: Integer", "?location: Location", "?flags: Integer"] + node.fields.map { |field| "?#{field.name}: #{field.rbs_class}" }).join(", ") %>) -> <%= node.name %>
    def copy(<%= (["node_id", "location", "flags"] + node.fields.map(&:name)).map { |field| "#{field}: self.#{field}" }.join(", ") %>)
      <%= node.name %>.new(<%= ["source", "node_id", "location", "flags", *node.fields.map(&:name)].join(", ") %>)
    end

    # def deconstruct: () -> Array[nil | Node]
    alias deconstruct child_nodes

    # def deconstruct_keys: (Array[Symbol] keys) -> { <%= (["node_id: Integer", "location: Location"] + node.fields.map { |field| "#{field.name}: #{field.rbs_class}" }).join(", ") %> }
    def deconstruct_keys(keys)
      { <%= (["node_id: node_id", "location: location"] + node.fields.map { |field| "#{field.name}: #{field.name}" }).join(", ") %> }
    end
    <%- if (node_flags = node.flags) -%>
    <%- node_flags.values.each do |value| -%>

    # def <%= value.name.downcase %>?: () -> bool
    def <%= value.name.downcase %>?
      flags.anybits?(<%= node_flags.name %>::<%= value.name %>)
    end
    <%- end -%>
    <%- end -%>
    <%- node.fields.each do |field| -%>

    <%- if field.comment.nil? -%>
    # attr_reader <%= field.name %>: <%= field.rbs_class %>
    <%- else -%>
    <%- field.each_comment_line do |line| -%>
    #<%= line %>
    <%- end -%>
    <%- end -%>
    <%- case field -%>
    <%- when Prism::Template::LocationField -%>
    def <%= field.name %>
      location = @<%= field.name %>
      return location if location.is_a?(Location)
      @<%= field.name %> = Location.new(source, location >> 32, location & 0xFFFFFFFF)
    end
    <%- when Prism::Template::OptionalLocationField -%>
    def <%= field.name %>
      location = @<%= field.name %>
      case location
      when nil
        nil
      when Location
        location
      else
        @<%= field.name %> = Location.new(source, location >> 32, location & 0xFFFFFFFF)
      end
    end
    <%- else -%>
    attr_reader :<%= field.name %>
    <%- end -%>
    <%- end -%>
    <%- node.fields.each do |field| -%>
    <%- case field -%>
    <%- when Prism::Template::LocationField -%>
    <%- raise unless field.name.end_with?("_loc") -%>
    <%- next if node.fields.any? { |other| other.name == field.name.delete_suffix("_loc") } -%>

    # def <%= field.name.delete_suffix("_loc") %>: () -> String
    def <%= field.name.delete_suffix("_loc") %>
      <%= field.name %>.slice
    end
    <%- when Prism::Template::OptionalLocationField -%>
    <%- raise unless field.name.end_with?("_loc") -%>
    <%- next if node.fields.any? { |other| other.name == field.name.delete_suffix("_loc") } -%>

    # def <%= field.name.delete_suffix("_loc") %>: () -> String?
    def <%= field.name.delete_suffix("_loc") %>
      <%= field.name %>&.slice
    end
    <%- end -%>
    <%- end -%>

    # def inspect -> String
    def inspect
      InspectVisitor.compose(self)
    end

    # Return a symbol representation of this node type. See `Node#type`.
    def type
      :<%= node.human %>
    end

    # Return a symbol representation of this node type. See `Node::type`.
    def self.type
      :<%= node.human %>
    end

    # Implements case-equality for the node. This is effectively == but without
    # comparing the value of locations. Locations are checked only for presence.
    def ===(other)
      other.is_a?(<%= node.name %>)<%= " &&" if (fields = [*node.flags, *node.fields]).any? %>
        <%- fields.each_with_index do |field, index| -%>
        <%- if field.is_a?(Prism::Template::LocationField) || field.is_a?(Prism::Template::OptionalLocationField) -%>
        (<%= field.name %>.nil? == other.<%= field.name %>.nil?)<%= " &&" if index != fields.length - 1 %>
        <%- elsif field.is_a?(Prism::Template::NodeListField) || field.is_a?(Prism::Template::ConstantListField) -%>
        (<%= field.name %>.length == other.<%= field.name %>.length) &&
        <%= field.name %>.zip(other.<%= field.name %>).all? { |left, right| left === right }<%= " &&" if index != fields.length - 1 %>
        <%- elsif field.is_a?(Prism::Template::Flags) -%>
        (flags === other.flags)<%= " &&" if index != fields.length - 1 %>
        <%- else -%>
        (<%= field.name %> === other.<%= field.name %>)<%= " &&" if index != fields.length - 1 %>
        <%- end -%>
        <%- end -%>
    end
  end
  <%- end -%>
  <%- flags.each_with_index do |flag, flag_index| -%>

  # <%= flag.comment %>
  module <%= flag.name %>
    <%- flag.values.each_with_index do |value, index| -%>
    # <%= value.comment %>
    <%= value.name %> = 1 << <%= (index + 2) %>
<%= "\n" if value != flag.values.last -%>
    <%- end -%>
  end
  <%- end -%>

  # The flags that are common to all nodes.
  module NodeFlags
    # A flag to indicate that the node is a candidate to emit a :line event
    # through tracepoint when compiled.
    NEWLINE = 1

    # A flag to indicate that the value that the node represents is a value that
    # can be determined at parse-time.
    STATIC_LITERAL = 2
  end
end
